Cobalt imidazolate frameworks are classical electrocatalysts for the oxygen evolution reaction (OER) but suffer from the relatively low activity. Here, a non‐3d metal modulation strategy is presented ...for enhancing the OER activity of cobalt imidazolate frameworks. Two isomorphous frameworks Co4(MO4)(eim)6 (M=Mo or W, Heim=2‐ethylimidazole) having Co(eim)3(MO4) units and high water stabilities were designed and synthesized. In different neutral media, the Mo‐modulated framework coated on a glassy carbon electrode shows the best OER performances (1 mA cm−2 at an overpotential of 210 mV in CO2‐saturated 0.5 m KHCO3 electrolyte and 2/10/22 mA cm−2 at overpotential of 388/490/570 mV in phosphate buffer solution) among non‐precious metal catalysts and even outperforms RuO2. Spectroscopic measurements and computational simulations revealed that the non‐3d metals modulate the electronic structure of Co for optimum reactant/product adsorption and tailor the energy of rate‐determining step to a more moderate value.
Non‐3D for 3D: Introducing non‐3d metal oxide units into a cobalt imidazolate framework results in the drastic enhancement of electrocatalytic performance of the oxygen evolution reaction in neutral media.
Lack of detailed knowledge of SARS-CoV-2 infection has been hampering the development of treatments for coronavirus disease 2019 (COVID-19). Here, we report that RNA triggers the liquid-liquid phase ...separation (LLPS) of the SARS-CoV-2 nucleocapsid protein, N. By analyzing all 29 proteins of SARS-CoV-2, we find that only N is predicted as an LLPS protein. We further confirm the LLPS of N during SARS-CoV-2 infection. Among the 100,849 genome variants of SARS-CoV-2 in the GISAID database, we identify that ~37% (36,941) of the genomes contain a specific trio-nucleotide polymorphism (GGG-to-AAC) in the coding sequence of N, which leads to the amino acid substitutions, R203K/G204R. Interestingly, N
exhibits a higher propensity to undergo LLPS and a greater effect on IFN inhibition. By screening the chemicals known to interfere with N-RNA binding in other viruses, we find that (-)-gallocatechin gallate (GCG), a polyphenol from green tea, disrupts the LLPS of N and inhibits SARS-CoV-2 replication. Thus, our study reveals that targeting N-RNA condensation with GCG could be a potential treatment for COVID-19.
Separations and analyses of chiral compounds are important in many fields, including pharmaceutical production, preparation of chemical intermediates, and biochemistry. High‐performance liquid ...chromatography using a chiral stationary phase is regarded as one of the most valuable methods for enantiomeric separation and analysis because it is highly efficient, is broadly applicable, and has powerful separation capability. The focus for development of this method is the identification of novel chiral stationary phases with superior recognition performance and good stability. The present article reviews recent progress in the development of new chiral stationary phases for high‐performance liquid chromatography between January 2018 and June 2021. These newly reported chiral stationary phases are divided into three categories: small organic molecule‐based (cyclodextrin and its derivatives, macrocyclic antibiotics, cinchona alkaloids, and other low molecular weight chiral molecules), macromolecule‐based (cellulose and amylose derivatives, chitin and chitosan derivatives, and synthetic helical polymers) and chiral porous material‐based (chiral metal‐organic frameworks, chiral covalent organic frameworks, and chiral inorganic mesoporous silicas). Each type of chiral stationary phase is discussed in detail.
Covalent triazine frameworks (CTFs) are normally synthesized by ionothermal methods. The harsh synthetic conditions and associated limited structural diversity do not benefit for further development ...and practical large‐scale synthesis of CTFs. Herein we report a new strategy to construct CTFs (CTF‐HUSTs) via a polycondensation approach, which allows the synthesis of CTFs under mild conditions from a wide array of building blocks. Interestingly, these CTFs display a layered structure. The CTFs synthesized were also readily scaled up to gram quantities. The CTFs are potential candidates for separations, photocatalysis and for energy storage applications. In particular, CTF‐HUSTs are found to be promising photocatalysts for sacrificial photocatalytic hydrogen evolution with a maximum rate of 2647 μmol h−1 g−1 under visible light. We also applied a pyrolyzed form of CTF‐HUST‐4 as an anode material in a sodium‐ion battery achieving an excellent discharge capacity of 467 mAh g−1.
Layered allrounder: A novel polycondensation approach enables the construction of covalent triazine frameworks (CTFs) under mild conditions from a wide array of building blocks. The resulting CTFs present a new type of layered material with potential applications in separations, photocatalysis, and energy storage.
Jin-Ling Tang and Li-Ming Li argue that despite the lure of vaccines and new drugs, established public health measures will remain our best tool to control covid-19 and future epidemics
This paper contributes to the development of randomized methods for neural networks. The proposed learner model is generated incrementally by stochastic configuration (SC) algorithms, termed SC ...networks (SCNs). In contrast to the existing randomized learning algorithms for single layer feed-forward networks, we randomly assign the input weights and biases of the hidden nodes in the light of a supervisory mechanism, and the output weights are analytically evaluated in either a constructive or selective manner. As fundamentals of SCN-based data modeling techniques, we establish some theoretical results on the universal approximation property. Three versions of SC algorithms are presented for data regression and classification problems in this paper. Simulation results concerning both data regression and classification indicate some remarkable merits of our proposed SCNs in terms of less human intervention on the network size setting, the scope adaptation of random parameters, fast learning, and sound generalization.
The essence of rational design syntheses of functional inorganic materials lies in understanding and control of crystal structures that determine the physical properties. AgGaS2 has the highest ...figure of merit for IR nonlinear optical interactions to date, but suffers low laser‐induced damage threshold (LIDT). The partial Li substitution of Ag atoms is now shown to push up the bottom of the conduction band and flatten the top of the valence band, leading to an ultrawide band gap of 3.40 eV (record high for AgGaS2, indicating a transparency edging nearly 180 nm shorter than that of AgGaS2), which gives Li0.60Ag0.40GaS2 a LIDT 8.6 times stronger when AgGaS2 is compared. Li0.60Ag0.40GaS2 exhibits 1.1 times stronger nonlinear susceptibility, which is because the energy‐favorable Li substitution gradually decreases the sulfur dislocation in the lattice, which allows a better geometric superposition of nonlinear optical tensors.
Lithium substitution maintains the symmetry of AgGaS2 structure and leads to an ultrawide band gap, simultaneously enhanced laser induced damage threshold (LIDT), and large second harmonic generation (SHG) that are otherwise inversely correlated. These enhancements are governed by the energy‐favorable decrease in dislocation in the lattice.
Patterning multiple images within a single element without crosstalk can significantly increase the information capacity and security, but it is challenging to enable the response capability in each ...image. Now, the patterning of crosstalk‐free yet cooperative‐thermoresponse images (holographic and fluorescent images) is successfully achieved by designing a liquid crystal (LC)/AIEgen system with a unique synergy. The AIEgen's fluorescence intensity is controlled by the LC, while the LC's phase transition is in turn promoted by the AIEgen. The fluorescent image contrast is significantly boosted by efficient energy transfer (ΦET: 96 %) from the LC to the AIEgen. The AIEgen's photocyclization for fluorescent patterning occurs in a zero‐order kinetic manner and can be completed within several minutes when assisted by the LC. The photocyclization conversion is quantitatively dependent on the aggregation size: α∼exp(‐d), and able to reach as high as 98 %.
Cooperation without talking: An AIEgen/liquid crystal (LC) system with unique synergistic interactions was designed to pattern noninterference images (holographic and fluorescent) with unprecedented cooperative thermoresponse. The AIEgen's fluorescence intensity is controlled by the LC, while the LC's phase transition is in turn promoted by the AIEgen.
The separation of enantiomers by chromatographic methods, such as gas chromatography, high‐performance liquid chromatography and capillary electrochromatography, has become an increasingly ...significant challenge over the past few decades due to the demand of pharmaceutical, agrochemical, and food analysis. Among these chromatographic resolution methods, high‐performance liquid chromatography based on chiral stationary phases has become the most popular and effective method used for the analytical and preparative separation of optically active compounds. This review mainly focuses on the recent development trends for novel chiral stationary phases based on chitosan derivatives, cyclofructan derivatives, and chiral porous materials that include metal‐organic frameworks and covalent organic frameworks in high‐performance liquid chromatography. The enantioseparation performance and chiral recognition mechanisms of these newly developed chiral selectors toward enantiomers are discussed in detail.
Fractal time series substantially differs from conventional one in its statistic properties. For instance, it may have a heavy-tailed probability distribution function (PDF), a slowly decayed ...autocorrelation function (ACF), and a power spectrum function (PSD) of 1/f type. It may have the statistical dependence, either long-range dependence (LRD) or short-range dependence (SRD), and global or local self-similarity. This article will give a tutorial review about those concepts. Note that a conventional time series can be regarded as the solution to a differential equation of integer order with the excitation of white noise in mathematics. In engineering, such as mechanical engineering or electronics engineering, engineers may usually consider it as the output or response of a differential system or filter of integer order under the excitation of white noise. In this paper, a fractal time series is taken as the solution to a differential equation of fractional order or a response of a fractional system or a fractional filter driven with a white noise in the domain of stochastic processes.
PDF
